使用自定义UIImagePicker叠加导致白色空白屏幕相机预览

Question

我目前正在为我的相机控件和UIImagePickerController使用自定义叠加层，并进行以下设置：

self.imagePickerController = [[UIImagePickerController alloc] init];
    self.imagePickerController.delegate = self;
    //... Additional set up code omitted
    self.imagePickerController.mediaTypes = [[NSArray alloc] initWithObjects: (NSString *) kUTTypeImage, nil];
    //!---- If below code deleted and use default ImagePickerController, all works fine
    if (self.imagePickerController.sourceType == UIImagePickerControllerSourceTypeCamera)
    {
        self.imagePickerController.showsCameraControls = NO;

        [[NSBundle mainBundle] loadNibNamed:@"overlayView2" owner:self options:nil];
        self.overlayView.frame = self.imagePickerController.cameraOverlayView.frame;
        self.imagePickerController.cameraOverlayView = self.overlayView;
        self.overlayView = nil;

        CGSize screenSize = [[UIScreen mainScreen] bounds].size;

        float cameraAspectRatio = 4.0 / 4.0;
        float imageWidth = floorf(screenSize.width * cameraAspectRatio);
        float scale = ceilf((screenSize.height / imageWidth) * 10.0) / 10.0;

        self.imagePickerController.cameraViewTransform = CGAffineTransformMakeScale(scale, scale);

    }

使用上面的代码，我得到以下白色相机预览屏幕：

但是，根据上述评论，如果我使用默认的UIImagePickerController，那么预览将启动并正常工作：

我不确定设置的哪些方面导致白色空白屏幕。一个关于类似问题的question提到录音，但由于我只专注于图片，我不确定它是如何相关的。

感谢您的帮助！